U.S. Pat. No. 4,649,810 issued to Wong and entitled "Automatic Cooking Apparatus" discloses an integrated cooking apparatus for automatically preparing culinary dishes. In one embodiment of that invention, the recipe ingredients are pre-loaded into a compartmentalized carousel, which rotates on command under the control of a microprocessor to bring the appropriate compartment into position for dispensing its ingredients into a cooking vessel. The ingredients are then heated, stirred, covered and uncovered automatically according to a prescribed recipe. For such an automatic cooking apparatus to be able to reproduce a variety of dishes with the delicacy of the accomplished cook, the automatic stirring mechanism must be able to stir, mix, turn, or agitate the ingredients in the manner of the live cook.
In the course of preparing a dish, a cook may be called upon to perform a range of complex motions referred to by such various terms as stirring mixing, turning, folding, blending, or flipping. Where it is not necessary to distinguish among them, such motions are often referred to herein simply as "stirring."
Manual stirring with a fork, spoon, spatula, or the like, may involve a complex motion. Depending upon the recipe and the nature of the food ingredients, the stirring implement may be moved in any one of a variety of patterns, which are difficult to reproduce by mechanical apparatus, and especially by a low-cost compact mechanical apparatus suitable for use with a typical cooking vessel of the type found in a domestic kitchen.
In the stirring mechanism disclosed in U.S. Pat. No. 4,649,810, for example, the action is produced by a blade generally conforming to the shape of the bottom of the cooking vessel. The blade is mounted on a vertical shaft at the center of the vessel, and the shaft is coupled to a motor drive providing the rotational force. As the blade revolves around the vertical axis defined by the shaft, it moves along the bottom and pushes the ingredients along, causing the ingredients to spread and to roll over the top of the blade.
This type of blade and mechanism will perform adequately for many recipes. However, it does not stir the ingredients quite in the same manner as a chef would, and for certain types of softer ingredients it may tend to break up or disfigure the ingredients excessively, adversely affecting the appearance and texture of the final dish.
Other automatic stirring mechanisms are known, but these generally call for awkward mechanical arrangements or are designed for specialized situations. One such stirring mechanism, intended for Chinese cooking with a wok, is disclosed in U.S. Pat. No. 4,503,502 to Chapin entitled "Method and Apparatus For Automated Chinese Stir-Fry Cooking." In that mechanism a small shovel-like implement is moved up and down in a vertical plane by a camming arrangement while another arrangement rotates the whole wok underneath the shovel. The resulting motion is such that the ingredients lying in the path of the shovel are "tossed" into the air a shovel-full at a time.
Another known stirring mechanism, for use with a special cooking pot, is disclosed by Wallman in U.S. Pat. No. 3,905,585 entitled "Agitating Device." The Wallman mechanism is mounted on the rim of the pot, which includes a special lip for this purpose. A shaft extends into the pot and terminates in a comparatively small, fixed stirrer. The mounting mechanism is structured such that the shaft rotates about its axis and simultaneously is "walked" around the perimeter of the pot. The rotating stirrer produces a localized circular stirring action as it is carried around the pot perimeter.
The Wallman device is awkward in that it requires a pot formed with the proper lip for mounting the device, which takes up much space about the rim. So, for example, the pot would be difficult to cover while the Wallman device is in position. Moreover, while the Wallman device may be suitable for agitating liquids, it does not reproduce the full effect of a stirring action such as might be used, for example, in quick-stir frying of Chinese foods.